[Kea-users] DHCPv6 option 16 and built in client class

Fri Dec 2 00:27:04 UTC 2022

I don't presently have DHCPv6 setup in my home network, but my kea
server for DHCPv4 seems to be assigning the clients to the vendor
classes:

2022-12-01 19:22:40.600 DEBUG [kea-dhcp4.packets/4325.139964547753856]
DHCP4_QUERY_DATA [hwtype=1 5c:a6:e6:46:d1:8c],
cid=[01:5c:a6:e6:46:d1:8c], tid=0x3d90730c, packet details:
local_address=192.168.40.2:67, remote_address=192.168.40.1:67,
msg_type=DHCPREQUEST (3), transid=0x3d90730c,
options:
  type=012, len=009: "TL-WA1201" (string)
  type=053, len=001: 3 (uint8)
  type=055, len=010: 1(uint8) 3(uint8) 6(uint8) 12(uint8) 15(uint8)
28(uint8) 33(uint8) 42(uint8) 121(uint8) 249(uint8)
  type=057, len=002: 1024 (uint16)
  type=060, len=008: "MSFT 5.0" (string)
  type=061, len=007: 01:5c:a6:e6:46:d1:8c

===============================================================

2022-12-01 19:22:40.592 DEBUG [kea-dhcp4.dhcp4/4325.139964547753856]
DHCP4_CLASS_ASSIGNED [hwtype=1 5c:a6:e6:46:d1:8c],
cid=[01:5c:a6:e6:46:d1:8c], tid=0x3d90730c: client packet has been
assigned to the following class(es): ALL, VENDOR_CLASS_MSFT 5.0, KNOWN

===============================================================

Sorry I can't be of more help, but I don't really have anywhere to
test DHCPv6 at the moment.

On Thu, Dec 1, 2022 at 7:44 AM Xuo Guoto via Kea-users
<kea-users at lists.isc.org> wrote:
>
> Hello list,
>
> I am trying to configure kea dhcpv6 to allocate prefix from a specific pool based on client classification based on vendor class option.
>
> The kea config is: (showing only the subnet6 part)
>
>     "subnet6": [
>       {
>         "id": 1,
>         "subnet": "2404:640:4003:2600::/56",
>         "pools": [
>           {
>             "pool": "2404:640:4003:2600:0:0:0:1 - 2404:640:4003:263f:ffff:ffff:ffff:fffe"
>           }
>         ],
>         "pd-pools": [
>           {
>             "prefix": "2404:640:5878:2640::",
>             "prefix-len": 58,
>             "delegated-len": 64
>           },
>           {
>             "prefix": "2404:640:5878:2680::",
>             "prefix-len": 58,
>             "delegated-len": 64
>           },
>           {
>             "prefix": "2404:640:5878:26c0::",
>             "prefix-len": 58,
>             "delegated-len": 64,
>             "client-class": "VENDOR_CLASS_dhv6_pool"
>           }
>         ],
>         "option-data": [
>           {
>             "name": "dns-servers",
>             "data": "2404:640:4003:2640::dead:beef, 2404:640:4003:2640::cafe:babe"
>           }
>         ]
>       }
>     ],
>
> Based on https://kea.readthedocs.io/en/kea-2.2.0/arm/classify.html?highlight=vendor_class#built-in-client-classes
>
> <quote>
> Some classes are built-in, so they do not need to be defined. Vendor class information is the primary example: the server checks whether an incoming DHCPv4 packet includes the vendor class identifier option (60) or an incoming DHCPv6 packet includes the vendor class option (16). If it does, the content of that option is prepended with VENDOR_CLASS_ and the result is interpreted as a class.
> </quote>
>
> I expect that the dhcpv6 clients will be allocated IP from "2404:640:5878:26c0::" if the option 16 contains the value dhv6_pool, based on the above explanation.
>
> The dhcpv6 client sends a packet with following payload:
>
> localAddr=[::1]:0 remoteAddr=[fd40:761b:fff1:2::3]:546
> msgtype=3(REQUEST), transid=0xdd45f5
> type=00001, len=00010: 00:03:00:01:02:00:00:00:00:01
> type=00002, len=00014: 00:01:00:01:2a:f2:70:1e:5e:b2:d7:b4:94:54
> type=00003(IA_NA), len=00040: iaid=981586272, t1=1800, t2=2880,
> options:
>   type=00005(IAADDR), len=00024: address=2404:640:4003:2600::2, preferred-lft=3600, valid-lft=300
> type=00006, len=00002: 23(uint16)
> type=00008, len=00002: 0 (uint16)
> type=16, len=15,  enterprise id=0x96xx, data-len0=9, vendor-class-data0='dhv6_pool'
> type=00025(IA_PD), len=00041: iaid=1736983355, t1=1800, t2=2880,
> options:
>   type=00026(IAPREFIX), len=00025: prefix=2404:640:5878:2641::/64, preferred-lft=3600, valid-lft=300
> 2 relay(s):
> relay[0]: msg-type=12(RELAY_FORWARD), hop-count=1,
> link-address=fd40:761b:fff1:2::3, peer-address=fd40:761b:fff1:2::2, 0 option(s)
> relay[1]: msg-type=12(RELAY_FORWARD), hop-count=0,
> link-address=2404:640:4003:2600::, peer-address=fe80::ffff:ffff:ff00:1, 2 option(s)
> type=00018, len=00004: 00:00:00:04
> type=00079, len=00008: 00:01:02:00:00:00:00:01
>
>
> But kea is not recognizing the packet to be of class VENDOR_CLASS_dhv6_pool. Logs show the following:
>
> 2022-11-30 13:02:02.314 DEBUG [kea-dhcp6.dhcp6/1876234.139694032694912] DHCP6_CLASS_ASSIGNED duid=[00:03:00:01:02:00:00:00:00:01], tid=0xdd45f5: client packet has been assigned to the following class(es): UNKNOWN
>
> Subsequently its getting a prefix from another pool:
>
> 2022-11-30 13:02:02.314 DEBUG [kea-dhcp6.dhcpsrv/1876234.139694032694912] DHCPSRV_MEMFILE_ADD_ADDR6 adding IPv6 lease with address 2404:640:5878:2641::
> 2022-11-30 13:02:02.314 INFO  [kea-dhcp6.leases/1876234.139694032694912] DHCP6_PD_LEASE_ALLOC duid=[00:03:00:01:02:00:00:00:00:01], tid=0xdd45f5: lease for prefix 2404:640:5878:2641::/64 and iaid=1736983355 has been allocated for 300 seconds
>
> How can I ensure that the packet is correctly classified so that the address gets allocated fro the correct pool.
>
> X.
>
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